Process of preparing adsorbent clays



March 24, 1936. E M SLOCUM 2,034,996

PROCESS OF PREPARING ADSORBENT CLAYS Original Filed May 21, 1954 HEATINGT CHAMBER BLEACHED OILST ZA TREATING HEAT VWEQ HAHGEE BLEACHING C Y Q @gN E o :3 awe/WM D Bow/120 M620 CUM Patent nr. 24, we

PROQESS @F PREP; i? f-r- ADSORBENT WAYS Edward Iii. Sloc, Macon, Ga.

Original application May 21, 1934, Serial. No.

726,823. 2, 1935, Serial No. 152

Divided and this application January 6 Claims. "(comm-2) This inventionrelates to the bleaching of animal and vegetable oils and fats. It alsorelates to the activation of bleaching clays and to the recovery ofresidual oils or fats remaining in spent 5 bleaching clay after the useof such clay in the bleaching of animal and vegetable oils and fats.

This is a division of my copending application Serial No. 726,823, filedMay 21, 1934.

The principal object of thisinvention is to provide an improved processof bleaching animal and vegetable oils and fats wherein numerous of thedisadvantages attending similar processes here-' tofore employed areavoided.

An important object of the present invention is to provide a continuousprocess of bleaching animal and vegetable oils and fats.

A further object of the invention is to provide a process of bleachinganimal and vegetable oils and fats wherein the apparatus employed is ofmore simple and inexpensive character than the apparatus commonlyemployed in similar methods heretofore used.

A further object of the invention is to provide a process of bleachinganimal or vegetable oils and fats which is productive of a product ofsubstantially better color and stability than prior processes ofbleaching oils and fats.

A further object of the present invention is to provide an improvedprocess of activating bleaching clay.

A further object of the invention is to provide a bleaching clay whichis substantially free from water soluble electrolytes.

Another object of the invention is to provide :13 an improved process ofreclaiming oil from spent bleaching clay.

Another object of the invention is to provide a. process of reclaimingoils and fats from spent bleaching clay without utilizing theconventional 40' step of blowing the spent clay with air.

Other objects and advantages of the invention will become apparentduring the course of the following description.

The method in general use for bleaching animal 45 and vegetable fats andoils is to introduce a large trough is pumped back into the bleachingtank until turbidity disappears and asatisfactory color is obtained. Theoil rlmning from the filter press is then pumped into a storage tank,agitation. of the oil and clay being continued until all the oil 5 hasbeen filtered.

After all of the clay has been pumped into the filter press, it is thenblown with air and thereafter blown with steamfor the purpose ofremoving-the residual oil from the spent clay. The oil 0 so removed fromthe spent clay is very dark and poor in quality so that in most cases itcan be used only for making so-called soap powder.

The conventional procedure as referredto'above is often very detrimentalto the stability of the 15 oil so' processed. Its resistance to becomingran old is in many cases cut in half. Another disadvantage is that theoil is heated for a considerable period in the presence of air and incontact with iron, both or which are injurious to the 011. Moreover, theoil forms a hardened film of oxidized oil around the fibers of thecanvas filter cloths, reducingv speed of filtration and leading to'thebreaking of the cloths. There are several other recognized disadvantagesin the conventional bleaching procedure.

One of the most important disadvantaga from a commercial standpoint isthe fact that the oil lost in the spent clay runs from 18 to 45% of thedried spent clay. This is'by far the heaviest expense in bleaching oil.The value of the oil lost in the spent clay may be several times that ofthe clay used in the process. I

As a result of extensive research directedto improving thedisadvantageous conventional processes of bleaching animal or vegetableoils and fats, I have devised a method which avoids most of theobjectionable features of the present moth- 4 ed in common use.

In a broad way, my process comprises mixing 40 the required amount ofbleaching clayfor treating the volume of animal or vegetable fat or oilwith a portion of the material to be bleached to provide a, dispersionof the clay therein, to which dispersion may be added treating chemicalsof the character hereinafter referred to. This dispersion is thencontinuously mixed in-required amount with the unbleached oil or fat,the resulta -ing mixture thereafter being heated to'atemperaturefavorable to the bleaching of the oil or fat and agitated in a bleachingchamber, after which the mixture is. passed to a filter where thebleached material is separated from the spent bleaching clay. It isanimportant partof process that the material to be bleached is constantlymaintained out of contact with the air or oxidizing gases. This isaccomplished by employing a closed system which at all times is substantially' completely filled with the material ,under treatment,thereby excluding'air without necessity of the creation or maintenanceof a vacuum in thesystem; The commercial impor:

tance of my process is also dependent in part on the procedures which Iemploy for activating the bleaching clay prior to the use thereof in thebleaching process and for recovering oil or fat of good quality from thespent bleaching clay, as

. hereinafterjdescribed in detail.

In the accompanying drawing I have shown in diagrammatic form anassembly of apparatus suitable for use in the practice of my process.

Referring to the drawing, the numeral I 0 designates a storage. tank forthe oil or fat to be bleached, which tank is provided with outlet pipesH and I2. The outlet pipe H, which is provided with avalve i3, isadapted to deliver oil or fat into the mixing container H which ispreferably provided with a suitable mixing or agitating device IS. Thecontainer I4 is provided for preparing the oil or fat'dispersion ofbleaching clay, to which dispersion other treating chemicals may beadded. The pipe I 6 is adapted to deliver the bleached material from thepipe 2| is passed through the pipe 22 to a heat insulated heatinterchanger generally designated by the reference numeral 23, themixture passing through a coil 24 arranged within the heat interchanger23 and being discharged therefrom through the pipe 25 which connectswith a heating unit 26 having steam inlet and outlet pipes 21 and 28 andheating tubes 29 which may be arranged in the manner of the usual tubeboiler construction. The material which passes through the heating unit26 is delivered by the pipe 30 into a bleaching chamber 3| which isprovided with a stirring device preferably in the form of a screwconveyor. The material discharged from the bleaching chamber 3i ispassed through the pipe 32 to a coil 33 arranged in juxtaposition to thecoil 24 in the heat interchanger 23. The material under treatment isdischarged from the coil 33 through the pipe 34 which connects with aunion 35 from which the material may be directed through either of thevalved pipes 3'8 to a preselected one of a series of filters 31. Thefilters 31 may be of conventional type such as a leaf filter press, aconventional self-emptying filter press, a centrifugal filter, or thelike. While in the accompanying drawing only two filters are designated,it will be apparent that additional filters may be used where required.Each of the filters 31 is provided with an outlet 38 which is adapted todischarge the filtered animal or vegetable oil or fat into theconventional troughs 39 from which the filtered material is carried bypipes 40 which connect at the union 4| to a pipe 42 connected to a pump43 which is adapted to pump the bleached oil or fat through a pipe 43into a storage tank 55.

In the preferred practice of my process, specially activated bleachingclay is employed. This is recommended in all cases and is particularlydesirable where a leaf filter press is employed in the process and wherethe clay used would, in the absence of the special activation referredto, be high in water soluble electrolytes and particularly salts ofcalcium, magnesium and the like, which would form insoluble soaps in asubsequent treatment for removing residual oil from spent bleachingclay.

In order to provide the activated clay which I preferably'employ, theclay in the undried solid v gel state in which it comes from the groundis first subdivided to form granules approximately the size ofsmallpebbles. The subdivided clay is then introduced into a tankprovided with a mixing device and is covered with an acid solution whichis thereafter heated to a boiling temperature under ordinary pressure.The boiling is continued until laboratory test shows that the clay hasbeen sufliciently activated. This ordinarily requires from 6 to 10hours. In treating the clay with an acid solution, practically any acidmay be employed, either organic or inorganic, hydrochloric acid,sulfuric acid, and oxalic acid being but three of the many acids whichcan be employed. I have found that all of the acids are of about equalvalue and, therefore, it is preferable to use the cheapest, i. e.sulfuric acid. The acid solution which is employed is preferably ofabout 60% strength although it will be obvious that the strength of acidis subject to great, variation. The amount of the acid solution employedis also subject to great variation but it is recommended that sufficientacid solution be used to completely cover the subdivided particles ofclay in the-treating container.

After the boiling treatment has been carried out for the required periodoftime, the excess of acid solution is drawn off and water is sprayed onto the mass and permitted to trickle through. This sprayingtreatment'thoroughly washes out all water soluble electrolytes presentin the clay.

It is of course recognized that activation of bleaching clay by acidtreatment is an old procedure. However, in the processes heretoforeemployed it has been customary to treat dried crude bleaching clay withWater to reduce the clay to a pulp or mudded condition, after which theclay is treated with an acid. It has been found that it has beensubstantially impossible satisfactorily to remove water solubleelectrolytes from the clay thus treated and in no instance has it beenpossible to thoroughly wash such clays by spraying. As pointed outabove, I have discovered that if the clay is treated in the undriedsolid gel state in which it occurs in the ground instead of in the pulpor mud form in which it is usually treated, the water solubleelectrolytes may be conveniently and easily removed by merely sprayingwater over the particles of clay in a container. Tests have demonstratedthat bleaching clay activated in the manner described above issubstantially free from water soluble electrolytes, the amount of suchelectrolytes being reduced below about one-hundredth of one per cent.These clay particles after washing are suitable not only for drying andgrinding to produce a commercial bleaching clay but, without drying orgrinding, are suitable for other purposes, such as in water purificationsystems.

amount of oil to be bleached is weighed into the mixing tank It. Theamount of clay employed is determined in conventional manner bylaboratory test and, in general, ranges between approximately 0.5% and1.25% on the weight of the oil or fat to be bleached. From the storagetank ill, sufficient of the oil or fat therein is delivered through thepipe I I under the control of the valve l3 into the mixing tank M. Thisoil or fat should be at as low a temperature as the solidifying point ofthe oil or fat will allow and still have the material thoroughly liquid.This temperature is, roughly, between60 and F. The amount of materialintroduced into the mixing tank id from the storage tank i0 is subjectto considerable variation but I have found it advantageous to mix withthe bleaching clay about nine times its weight of oil or fat from thetank id. The agitator i5 is then started so as to mix the clay into asmooth dispersion with the oil or fat. As

'will be apparent, instead of using but one mixing tank Id, several suchtanks may be employed.

In preferred practice, I also introduce into the mixing tank id certaintreating chemicals to be incorporated with the dispersion therein.However, these chemicals may be added separately or together later inthe process by introducing them directly into the system or by the useof separate mixing tanks. However, in order to avoid unnecessaryhandling of materials, it is preferable to mix the treating chemicalswith the dispersion in the tank id.

One of the treating chemicals which I recommend be incorporated with thematerial to be bleached is an inhibitor of enzyme and bacterial action.I have discovered that water soluble halogen compounds are particularlysuitable for this purpose, such as ammonium and alkali metal bromides,fluorides, iodides and chlorides and their complex ions. In preferredpractice I employ sodium fluoride. Of the soluble halides, sodiumchloride is the least effective inhibitor but even it can be used withsome measure of success. The amounts of the soluble halides employedwill vary greatly as will be apparent to those skilled in the art. Theamount required is determined by subjecting the oil or fat to be treatedto the conventional stability test. Generally, the amount used willrange from onefiitieth of one per cent. to one-tenth of one per cent. onthe weight of the material to be bleached.

I have also found it advantageous to incorporate an anti-oxidant withthe dispersion in the mixing tank id, preferably one which does not tendto discolor animal and vegetable fats and oils. Various suitableanti-omdants are known, such as the various derivatives of pyrogailoland other strongly oxygen-absorbing organic chemicals, such asdiphenols. The anti-oxidant is generally employed only in traces, sayone-fiftieth oi one per cent. on the weight of the material beingbleached If desired, carbon black may also be incorporated in thedispersion prepared in the mixing tank id. As is well known, carbonblack is irequently employed in the bleaching of animal or vegetablefats and oils for the 'purpm of delaying rancidity. However, I havefound that it is not necessary to employ carbon black in the presentprocess and since its use may prove troublesome, I prefer not to employthis material. However, it can be employed if desired and, if used, itis introduced in the approximate amount of four pounds of carbon blackto one hundred thousand pounds of the material to be bleached.

Asset forth above, the treating chemicals need not beadded in the mixingtank id but may be subsequently introduced into the system; These arepreferably introduced in solution or suspension in a portion of the oilor fat being treated.

From the tank it? the dispersion therein is mixed by any suitable meanswith a definite volume of the oil or fat to be processed. In preferredpractice, I accomplish this by the use of pumps l l and 26 which conveythe dispersion from the tank id and the oil or fat to be processed fromthe tank It to the union lt'where the mixing takes place. The pumps areset so as to mix the correct volumes of the oil or fat from the storagetank ill, which ordinarily has been subjected to the usual preliminaryrefining treatment, with the dispersion from the tank it. For example,if preliminary tests indicated that 1% of the bleaching clay on theweight of the oil or fat should be employed. and a 10% clay dispersionhad been prepared in the tank M3, approximately nine parts of the oil orfat to be bleached would be mixed with one part oi the 10% dispersion.

After the mixing oi the unbleached material and the clay dispersion, themixture is passed through a heating device and the hot mixture is thensent through a closed container, equipped with a stirring device, ofsuch dimensions that the oil or fat leaving it has been bleached andpurified to the desired degree. apparatus should be designed so that,where an activated quick-bleach clay is employed, a perind of abouteight to fifteen minutes will be required for the passage of thematerial from its point of mixture, say at the union E9, to its point ofdischarge from the bleaching chamber. bleaching temperature to beemployed will, of course, vary considerably according to the materialunder treatment, the purpose for which the bleached material is to beemployed, and other factors well known in the art. As a general rule,the bleaching temperature employed varies rough- Ordinarily, the

ly from to 300 F. Since the present process safely allows the use ofhigh bleaching temperatures without injury to the oil, I prefer to heatthe oil to a high bleaching temperature, since the higher thetemperature, the better the bleach. f

In the preferred practice of my process, the mixture of material to bebleached and the clay dispersion is passed from its point of mixture atthe union it, through the pipe 22 into the coil 26 arranged in theinsulated heat interchanger 23 where there is imparted to the unbleachedmaterial a portion of the heat from bleached material passing in acountercurrent direction through the juxtaposed coil 33. The material ispassed from the coil 26 through the heating unit '26 where it is heatedup to an elevated temperature, say up to 300 F. Thereafter the materialis passed through the bleaching chamber 39 where it is thoroughlystirred by the screw conveyor therein. From the chamber 38 the bleachedmaterial and spent clay dispersion is passed through the coil 33 in theheat interchanger 23 and out of the heat interchanger through the pipe355. In the preferred practice of the process, the material passingthrough the pipe 36 has been cooled to a temperature in the neighborhoodof F.

The material at this point is then conducted to a suitable filter toremove the bleached oil or fat from the associated spent bleaching clay.In preferred practice, I employ a series of filters of sullicient numberso that there will be at least one filter available while the spent clayin the other filters is being removed therefrom or being treatedrected-through-the pipes 86. As shown, each. of

the pipes is provided with a'valvein order that'the materialfrom thepipe 34 may be directed'to th proper filter.

I'may useany suitable conventional filter such as a leaffilterpress, aso-called self-emptying filter presaa centrifugal filter or the like.The. bleached oil or fat passing through the filter is .then subjectedto such additional refining treatment as may be desired, such as aconventional deodoriaing treatment, after whichit is 'intrc'- duced intoa storage tank.

When the bleached oil or fat is to be left in storage tanks for anysubstantial period, it is preferable to store the material in contactwith a non-oxidizing gas such as methane, which may be derived fromnatural gas, nitrogen,- carbon dioxide or the like. When a fat or oil isto have a gas beaten into it to provide an emulsion of the fat or oilwith such gas, as isthe practicewith much of the compound shortening nowmanufactured a non-oxidizing gas such as methane, nitrogemcarbon dioxideor the like should be used in place of the air now commonly used. An oilor fat thus treated will be found to be more stable than a similar oilor fat which has had air beateninto it. 7

As stated above, in the ordinary process of bleaching animal orvegetable fats and oils there is ordinarily lost about 18 to of the oilon the weight of the clay due to its retention by the spent bleachingclay and where a portion of this oil has been recovered, the quality ofthe recovered oil was so poor that it could not be marketed as highgrade oil. In the present process, I have provided a method of reducingthe oil loss to about 7% in one embodiment and to about 15% in anotherembodiment of the process.

. Where theoil is filtered with conventional leaf filter presses, thefirst unit employed is closed after it has been used for sufiicient timeto render its further use impractical and the material under treatmentis then directed to another similar press which is ready for use. Thespent clay in the first unit is then washed with a cold or luke-warmsoap solution. Any convenient method of applying the soap to the spentclay may be employed. In preferred practice, there is sent through thefirst filter press unit containing spent clay and bleached oil. in itspress leaves an oil dispersion of a water soluble soap. The soap ispreferably suspended in a portion of the refined material being treated.For example, if cottonseed oil is being bleached, the soap is suspendedin refined cottonseed oil and this dispersion is forced through thepress under treatment. This is continued until sufficient soap has beendeposited in. the spent clay to permit it to be washed thoroughly. Theamount of soap to be deposited will vary according to the particularconditions in a particular plant but, in general, the soap wouldapproximate between one-tenth of one per cent. and one per cent. on theweight of the spent clay to be processed.

When a sufiicient amount of soap has been deposited the supply of theoil dispersion of soap is cut off and cold or lukewarm water is thensent through the spent clay in the press. If too hot water he sentthrough the spent clay it will not hydrate the clay sufficiently toreduce the surface attraction of the clay for the oil.

The water passing through the spent clay washes the liberated oilthrough, thefiltercloths and the resulting mixture of oil and water isthen introduced into a container where it is permitted to stand so thatthe'oil may beseparated from channels. Thereafter, water is againintroduced into the press and this may again befollowed by a secondtreatment with an elastic gas such as steam and a third treatment withwater.

As a result of this treatment the oil lost in the spent clay may bereduced to approximately 15%- of the dry spent clay.-

There are several other advantages attending this method of treatingspent clay in leaf filter.-

presses. The bleached oilis" removed from the filter press substantiallycompletely without blowing the press with air as is now the usualmethod. This use of air injures the oil removed by it, as well as theoil still remaining with the spent clay in the press.

After the treatment described, the press cloths are washed with soapywater following each use of the filter press. The amount of oil left onthe fibers of the press cloths is definitely lessened. The press clothsare thus cleaner, they filter more freely, and last longer.

Where in the above referred to treatment cold or lukewarm water is used,the alkaline soap solution reduces the free fatty acids in the recovered oil. The soap also dissolves some of the color from the recoveredoil. What color is developed is very readily bleached out so that therecovered oil without loss of quality in the finished product can beadded to the next batch of oil to be bleached. This is not true of theoil recovered by the air-steam blow method.

The above described treatment of the spent clay with soap is successfulonly with bleaching clay whose content of soluble lime and magnesia, andother injurious metallic salts, is low enough not to form insolublemetallic soaps on the surface of the clay particles and so prevent thepassage of liquid through the spent clay. Therefore, as pointed outabove, when filtering is done with a leaf filter press and the rawbleaching clay contains a substantial amount of these injuriouscompounds, the clay should be activated in the manner described above inorder that the clay may be substantially freed from water solubleelectrolytes.

Instead of using a leaf filter press for separating the bleached oil orfat from the spent bleaching clay, I may use any convenient known typeof self-emptying filter press or any convenient known type ofcentrifugal filter. If a self-emptying press is employed, metallicfilter cloths can be used. If a centrifugal filter is employed I preferto use a type which can be rapidly freed of the solid phase and also atype in which an inert gas atmosphere can be maintained in contact withthe filtering oil or fat.

Where a self-emptying press or a centrifugal filter is used, it ispreferable to treat the oily spent clay apart from the filter ratherthan in the filter as where a leaf filter press is employed.

iii

aoeaoee Accordingly before treating the spent clay to recovertherefromthe oil or fat retained thereby, the spent clay should firstbe removedfrom either the self-emptying filter or the centrifugal filter.

The spent clay which has been removed from the filter is preferably runinto a tank which When the water has thus been run in, the oil or fatwhich has been liberated by the treating chemical rises to the top whilethe clay settles to the bottom as a thin mud. The oil is then lhawn ofifrom the surface of the water and the clay mud run into the sewer. Sincethe spent clay remains in a light condition which will not form heavygummy deposits it can be safety emptied into a sewer. By the abovetreatment the oil or fat present in the clay is reduced to about 7% onthe weight of the dry spent clay.

I have found that there are three difierent classes oi reagents whichmay be employed to reduce the surface adhesion of the spent clay towardthe oil or fat in the treatment above described. For example, solublefluorides may be satisfactorily employed, and I prefer to use an aqueoussolution of sodium fluoride for miring with the spent clay to beprocessed. The amount of sodium fluoride to be employed in preparing theaqueous solution will, of course, vary substantially but the exactamount can readily be determined by previous laboratory trial.Ordlnarily sodium fluoride in the amount or from V of 1% to A; of 1% onthe weight of the clay is sumcient.

A second class of reagents capable oi reducing the surface attraction ofthe spent bleaching clay for certain oils and fats are coagulatingpolyvalent kations, specifically, soluble salts of iron, manganese,chromium and aluminum. When one of these metallic salts is employed itmay be present, for example, to the extent of from 1 to.1o% on theweight of the spent clay being treated.

A third class of reagents capable of reducing the surface attraction ofthe spent clay for cer== tain oils and fats are coagulating polyvalentanions, specifically, soluble salts of amphoteric metal acids, such assodium aluminate, sodium stannate, sodium tungstate and the like. Whenone of these salts is employed it may be present, for example, to theextent of say of 1% to 5% on the weight of the spent clay being treated.

After the oil or fat which has been separated from the spent clay hasbeen recovered, it is ordinarily advisable to add the recovered materialto another batch of oil or fat to be bleached, although insome-instances this will not be found desirable since the materialwithout further treatment may be put to other uses than the main body ofoil or fat which has been bleached.

As will be apparent from the foregoing, my process possesses numerousadvantages over the processes heretofore employed for the bleaching ofanimal and vegetable oils and fats. In the first place, the process is acontinuous one which is obviously a very important advantage over theprior art processes customarily employed. Moreover, the processmaintains the oil or fat out of contact with any great quantity of airor oxidizing gas throughout the process and yet avoids the necessity ofcreating or mainta a vacuum in the system. Where a quick bleaching clayis employed, as in the preferred practice or the process, a smallapparatus can be employed.

Such a small apparatus may, without running into prohibitive expense, bemade of metals or alloys more suitable than the iron or brass now incommon use in bleaching kettles and filter processes. Another importantadvantage or the process is that there is no necessity to blow the 4niter medium with air to decrease the amount of oil entrained thereby.The oil or fat recovered in the process is oi lower acid content and inbetter condition than the oil recovered by the present air and steamtreatment. The oil lost in the spent clay is substantially smaller in.

amount than that lost after air-steam blowing. There is no solvent lostnor solvent to be removed from the recovered oil or fat as in theorganic solvent methods of recovery from spent clay. Where leaf pressesare used for filtering, the

press cloths are left cleanen-filter more rapidly and last longer thaninthe case of prior processes using leaf presses. used for filtering inthe process, if desired. the oily spent clay from self-emptying pressescan be easily treated to give low oil retention. The spent clay aftertreatment to remove entrained oil or fat is a light pulp which can berun into a sewer without difficulties resulting from gummy changersbetween bleached and unbleached oils.

The optimum bleaching temperature can be maintained in the bleachingchamber while maintaining the oil or fat out or contact with the airwithout the necessity of creating or maintaining a vacuum in thebleaching chamber. If self-emptying presses or inert gas types ofcentrifugals are employed, the oil can be filtered at temperatures mostconvenienu for rapid filtration and the oil can yet be kept out ofcontact with the air. The use of an inhibitor of enzyme and bacterialaction not only inhibits the lipasesplitting of vegetable and animalfats and oils but these inhibitors also serve as disinfecting agentsagainst moulds, yeast and bacteria. Since the water soluble halidesemployed as inhibitors Self-emptying pressescan be are insoluble in oilsand fats, they do not afiect the oils or fats themselves. When thedispersed crystals come in contact with wet colloidal seed pulpdispersed in oil, the lipase in it is rendered inefiective and the pulpmaterial itself is no longer food for moulds, yeast and bacteria. Oilsand fats stored in contact with an inert gas or in which an inert gashas been dispersed possess increased protection against oxidation.Finally, it has been demonstrated that the animal and vegetable oils andfats processed in accordance with the present invention are stableagainst rancidlty for a substantially longer period than the oils andfats treated in accordance with the usual prior practice.

The term bleaching clay" as employed herein is not intended to berestrictive to any one class of clays, but is to be understood asincluding all arglllaceous material, such as bentonlte, semiis adaptedto remove color from vegetable andanimal oils andfats.

In the practice of the above described process,

the water which is employed in washing the ac- .tration of injuriousions.

tivated bleaching clay after it has been subjected I to an activatingagent should be low in concen- For example, a water approaching zerohardness should be employed.

Obviously, materials other than acids may be ,used in activatingbleaching clays and it is an important feature of my invention thatwhere the bleaching clay is activated either with an acid or otheractivating agents, the water soluble materials remaining in the clay canbe readily washed out if the clay is treated in the form of claygranules in solid gel state. While I have referred above to the washingof such clay granules by spraying water thereon and permitting the waterto trickle through'the mass, it will be apparent that washing may beaccomplished by any other suitable means which involves the relativemovement of the washing water with respect to the clay. granules.

As pointed out above, I prefer to employ in the practice of the presentprocess an inhibitor of enzyme and bacterial action which comprises asoluble halide. .While, as stated, this material is preferably added tothe oil dispersion of clay in the mixing tank [4, and passes through thesystem in the presence of the clay, to be substantially filtered outwhen the bleached material is passed through the filter, I havediscovered that it is also advantageous in treating edible fats and oilswhich are not bleached or which may not be bleached by a process of thecharacter above described to add to such edible fat or oils 2. minorproportion of a water soluble but oil insoluble halide and, thereafter,to substantially remove the crystals of the halide as by filtering.While the filtering will remove the major proportion of the crystals ofthe halide, there will still be left traces of the halide which will besufiicient to exhibit enzyme and bacterial action without injuring thedigestibility of the treated oil or fat. As is well known, in expressingedible oils from nuts or seeds, the nuts or seeds are cut into smallpieces and subjected to great pressure whereby the oil is pressed out.This oil always contains a considerable roportion of pectinous materialfrom the cells of the nuts and seeds. While a substantial proportion ofthis pectinous material can be removed by filtration and othertreatment, a portion of this organic material which is present incolloidal condition cannot be removed. It is very finely dispersed inthe body of the oil so that it will pass through an ordinary filter. Itis this filterable dispersion of colloidal organic material which isconsidered to be responsible for the spoiling of the oil throughrancidity. By adding a water-soluble, oil-insoluble inhibitor of enzymeand bacterial action, as described above, the dispersion of pectinousmaterial present in the body of the oil will take up some of theinhibitor so as to prevent enzyme and bacterial action. As pointed outabove, the inhibitor preferably consists of a water-soluble,oil-insoluble halide, preferably a water-soluble, oil-insoluble fiuorinecompound, and this material is preferably added in the form of crystalsof small particle size. When the treated oil is filtered, the crystalsof the fluorine compound will be removed from the oil itself but a smallportion of the inhibitor will be dispersed in the filterable pectinousmaterial which is I. through the oil. Of course, the particles of-"thefluorine compound having been filtered out of the 1 oil itself and theamount of fluorine compound dispersed in the pectinous material beingsmall,

the final-product 'will not be injured with rc-' spect to taste ordigestibility, although stabilized against enzyme and bacterial action.

Where reference is made herein to activating;

bleaching clay it is to be understood that the term activating is usedin its common acsubjecting .of the bleaching clay to the action ofcepted technical sense, i. e. as applying to the 4 an acid solution toremove some but not all of f the basic constituents of the silicate.complex, whereby the resulting product remains as a hydrated silicate ofalumina and not a silicic acid.

The term bleaching clay as employed herein is used in its commonlyaccepted technical sense, i. e. as applyingto an argillaceous hydratedsilicate of alumina possessing marked adsorptive powers and having thecharacteristic of readily sliming, by which is meant that when dried andplaced in water or a conventional activa g acid solution it will readilydisintegrate into a slime or mud or pulp. The term does not include, and

is not intended to cover herein, shale-like substances containingnotable proportions of calcium and magnesium carbonate, such as certainfullers earths which are essentially rock-like. Moreover, the term doesnot include, and is not intended to cover herein, kaolins which do notpossess marked adsorptive powers either before or after treatment withan acid activating agent, or stable silicate aggregates, such as theglauconites or green sands, which are essentially rock sands.

While I have described in detail the preferred practice of my processand several modifications thereof, it is to be understood that thedetails of procedure, the arrangement of steps, the proportions ofingredients and the like,-may be variously modified without departingfrom the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In a process of activating readilysliming bleaching clay wherein theclay is subjected to the action of an acid solution and theacid-activated clay is thereafter washed, the improvement whichcomprises treating with the acid solution bleaching clay which is in itsoriginal gel-like form and which contains sufiicient of its originalwater content to prevent substantial disintegration of the clay into apulp or mud during the treatment with the acid solution.

2. In a process of activating readily sliming bleaching clay wherein theclay is subjected to the action of an acid solution to activate thesame, the improvement which comprises treating with the acid solutionbleaching clay which is in its original gel-like form and which hasretained up to the point of such treatment with acid solution suflicientof its original water content to prevent substantial disintegration ofthe clay into a pulp or mud during such treatment with acid solution,and washing the substantially nondisintegrated clay substantiallycompletely free from water-soluble electrolytes.

3. In a process of activating readily sliming bleaching-clay wherein theclay is treated with an acid solution to activate the same and theacid-activated clay is thereafter washed, the imment with acid solutionwhich comprises subjecting to the acid treatment bleaching clay whichisin solid gel-like state and which has substantially the same watercontent as said clay had when in the ground.

4. In a process of activating readily sliming bleaching clay wherein theclayin the form of subdivided lumps is treated with an acid solution toactivate said clay, the improvement for preventing substantial formationof a pulp or mud and for retaining the clay in said lump form upon saidacid treatment which comprises subjecting to the acid treatmentsubdivided lumps of bleaching clay which is in solid gel-like state andwhich has substantially the same water content as said clay had when inthe ground, and washing the resulting lumps of activated claysubstantially completely free from water-soluble electrolytes.

5. A product of the character described comprising lumps ofacid-activated clay in solid gellike state, the form of said lumps beingsubstantially the same as the form imparted to the original clay priorto acid-activation thereof, said original clay being of readily slimingtype, the

r lump form of said acid-activated clay permitting rapid washing thereofsubstantially completely to remove water-soluble electrolytes therefrom.

6. A product of the character described comprising an adsorbent,acid-activated clay in the form of lumps corresponding substantially tothe form of the original clay when subjected to acidactivation, saidoriginal clay being of readily sliming type, the clay in said lumpsbeing in undried solid gel-like state, said product being substantiallyfree from water-soluble electrolytes.

EDWARD M. SLOCUM.

